1. Field of the Invention
This invention relates to a method of and an apparatus for manufacturing a surface fastener by continuously molding a plate-like substrate member by extrusion using thermoplastic resin and for molding loop members from a fiber filament on the substrate member simultaneously with the molding of the plate-like substrate member.
2. Description of the Related Art
A surface fastener having hook members on opposite surfaces of a substrate member is disclosed in, for example, Japanese Patent Publication No. SHO 42-8749. In manufacturing the double-sided surface fastener disclosed in Japanese Patent Publication No. SHO 42-8749, loop members are formed by a multifilament and a monofilament woven on front and back surfaces, respectively, of a woven cloth, and then both filaments are heat-set, whereupon part of each of the monofilament loop members is cut to have a hook shape. The resulting surface fastener has a hook surface and a loop surface on the respective sides. Then the loop and hook members are fixed to the foundation woven fabric by applying resin to the fabric.
Although there is no specific disclosure about the manufacturing method and apparatus, a surface fastener having a mixture of hook members and loopsmembers existing on one surface of a substrate member is proposed by, for example, Japanese Utility Model Laid-Open Publication No. HEI 4-6908. This surface fastener also is made of fibers, and presumably its manufacturing method is the same as that disclosed in the above-mentioned publication.
In the meantime, Japanese Patent Laid-Open Publication No. HEI 1-238805 discloses a surface fastener manufactured by molding a substrate member and engaging members from synthetic resin. More particularly, FIG. 18 of the Publication shows a double-sided surface fastener in which a multiplicity of rows of mushroom-shape engaging members of the same synthetic resin material project from one surface of the substrate member and a multiplicity of rows of spherical-headed engaging members of the same synthetic resin material project from the other surface of the substrate member. According to the manufacturing principle of the double-sided surface fastener disclosed in the Publication, as is apparent from the description of the specification, a predetermined width of surface fastener having a multiplicity of engaging member rows is manufactured by joining a large number of small-width tape substrates edge to edge with an adhesive agent or an adhesive resin, with or without using a common connecting sheet on the back side.
Therefore, in manufacturing the surface fastener disclosed in Japanese Patent Laid-Open Publication No. HEI 1-238805, firstly a small-width tape having a longitudinal row of engaging members is molded continuously or discontinuously by injection or press, and then a necessary number of tapes are arranged laterally and the tape substrates are joined edge to edge with an adhesive agent or the like.
Further, the technology of extruding a substrate member using thermoplastic resin and, at the same time, molding hook members on one surface of the substrate member is already known by, for example, U.S. Pat. No. 3,312,583 and International Patent Application Japanese Publication No. HEI 1-501775. The molding method disclosed in U.S. Pat. No. 3,312,583 comprises extruding molten thermoplastic resin onto a circumferential surface of a drum-shape die wheel, in which a multiplicity of mold discs and a multiplicity of spacer plates are laminated alternately, forcing the resin into hook-member-forming cavities of the mold discs, then pressing the resin on the drum surface to form a substrate member, and pulling molded hook members out of the cavities along with the substrate member in timed relation to the rotation of the drum while the resin is cooled. The mold disc has in one side surface hook-shape cavities extending radially from the circumferential surface toward the center and space circumferentially at predetermined distances. The side surfaces of the spacer plate are flat. The reason why the spacer plate is needed is that the hook-shape cavities cannot be formed in a single mold.
However, the woven-cloth-type surface fastener disclosed in Japanese Patent Publication No. SHO 42-8749 has a characteristic feature in that as the flexibility of the woven cloth is combined with the flexibility of the monofilament, a very smooth touch can be achieved when books of the surface fastener are coupled with and uncoupled from the loop members of the companion surface fastener. Since the monofilament constituting the hook members is drawn, it is excellent in pulling strength and bending strength though small in cross-sectional area. Further, since the woven structure has a very high density of hook members, it is possible to obtain a high coupling rate and an adequate degree of durability for repeated use. However, since this woven-cloth-type surface fastener requires a large consumption of material and a large number of manufacturing steps, it is difficult to reduce the cost of production.
In manufacturing the double-sided surface fastener having engaging members of fibers on both the front and back surfaces of the woven foundation, unlike the ordinary woven-cloth-type surface fastener having engaging members on only one side, it is impossible to impregnate the resin into only the foundation avoiding the engaging members simply by applying resin to the foundation in order to fix the roots of the engaging members projecting from the front and back surfaces of the foundation as described in the above-mentioned Publication. Consequently it is very difficult to adequately fix the engaging members to the foundation without causing the engaging members to become rigid.
In the surface fastener disclosed in Japanese Utility Model Laid-Open Publication No. HEI 4-6908, if manufactured efficiently, it has the foregoing advantage because of its fibers. However, since a mixture of monofilament loops and multifilament loops exist on one surface of the substrate cloth, forming hook members by cutting only the nomofilament loops would require a very complex manufacturing process and an apparatus having a complicated mechanism, thus causing a poor rate of production and increasing the manufacturing cost.
Accordingly, it is understood that in the conventional surface fastener having engaging members and loop members it is difficult to guarantee high quality.
Further, manufacturing the molded surface fastener disclosed in Japanese Patent Laid-Open Publication No. HEI 1-238805 would require a very complex manufacturing process, as is apparent from the description in the Publication, and hence it is inefficient and poor in productivity so that mass production of double-sided surface fasteners having the structure shown in FIG. 18 of the Publication is virtually impossible due to the manufacturing principle.
According to the surface fastener manufacturing method disclosed in, for example, International Patent Application Japanese Publication No. HEI 1-501775, since the hook members formed on the substrate member are merely molded of resin without being drawn, they are rigid and markedly poor in engaging strength as compared to those of fibers having the same size.